Process of making isoprene.



STATES CARL RUDER, OF WANPSBEK, NEAR HAMBURG, GERMANY.

PROCESS OF MAKING ISOPBENE.

No Drawing.

To all whom it may concern:

Be it known that I, CARL RUDER, doctor of philosophy, manufacturer, asubject of the King of Bavaria, residing at Wandsbek, near Hamburg, inthe Kingdom of Prussia, German Empire, have invented certain new anduseful Improvements in Processes of Making Isoprene, of which thefollowing is a specification. Y

Tilden (Soc. 46, 417), and recently Har ries (Ann. 383, 228)'have shownthat the decomposition of vapor of turpentine oil by -means ofincandescent metal wires will pro duce isoprene, although only witha'very small yield. The last mentioned investiga- -tor has, however,obtained better yields by using lirnonene or pentine oil;

The production of dipentene forms the subject of the process described.in German dipentene instead of tur- Patent No. 254665, according towhich ter-- pinols, terpines or their hydrates are heated attemperatures below 500 degrees centi gradewith non-acid water=expellingsubstances having a catalytic action. y

I have discovered that terpineol, or terpine hydrate, which lattercompound, in certain circumstances, by dehydration yields. 'terpineol,and is therefore tobe considered as closely related to terpineol, theterm terr pineol substance being hereafter employed to designate eitheror both these compounds and to include oilscoii-taining either or bothof theseconipounds; may be converted clirectly into isoprene by heatingthe vapors thereof in a suitablemanner. In operating in this manner, itis unnecessary to employ a water-expelling substance having a catalyticreaction.

When working under ordinary pressure the yields are fairly high, butthey are in-' creased by heating the vapors in a-partial Vacuum or bydiluting the vapors with a neutral gas. Gaseous products are notproduced in any considerable quantity by splitting off which is contraryto. what is the case in the processes of German: Patents Nos.'252499 and241895,

The ordinary commercial terpineol is, as iswell known, a mixture ofvarious isomeric compounds having the formula (3 E 0 Specification ofLetters Patent.

Patented Feb. 117, 1914.

Application filed September 16, 1913. Serial No. 790,013.

which except one, are derived from cyclohexene Inc on,

V [This one compound is a derivative of'60 cyclohexane, being thel-methyll-i'sopropenyl cyclo-hexanol. (1),; having a melting pointof 32to' 33 degrees 0.

CH3 CH1 According to German Patent-No. 241895 isoprene has already beenproduced from another derivative of cyclohexanohnamelyl-methyl-cyclohexanol' (1) Obviously, however, it could not be deducedtherefrom that ter'pin'eol which is mainly composed of derivatives ofcyclohexene, would likewise yield isoprene when .heated to hightemperatures. Example: Terpineol or hydrated terpine -vious1y freed bydistillation over sodium -from any terpineol that may have passe over.

What I claim is 5 1. A. process of producing isoprene which comprisessubmitting the vapor of aterpineol substance under a pressure notexceeding atmospheric, to at temperaturo suiticiently high to producedecomposition of the 10 cyclic compounds.

2. A process of making isoprenc which comprises passing the vapor oftcrpineoi over a heated metal spiral, at a temperature suificlently hlghto produce decomposition of the cyclic compounds, with the production

